... Of the accused

Contraddittorio means a procedure attended by both sides in which they have the right to make representations

my take

the constitution states that any charge against a person cannot in principle be one-sided and must be subject to cross-examination
there are however exceptions on certain conditions, and one of this conditions is that the accused waves his/her right to cross-examination


http://www.overlex.com/leggiarticolo.asp?id=1624

..."Tuttavia, sono ammissibili delle precise deroghe al principio del contraddittorio nella formazione della prova. Pertanto, si rimanda alla disciplina del legislatore ordinario la disciplinadei casi in cui una determinata conoscenza, sia pur formata al di fuori del confronto dialettico fra le parti, è suscettibile di diventare prova. L’ammissibilità di questi casie la legittimità costituzionale dei medesimi si calibra sui tre concetti fondamentali del comma 5° dell’articolo 111 della Carta Costituzionale. Alla luce di quest’ultimo principio, si deve affermare che le deroghe sono ammissibili purché siano fondate su uno di questi tre presupposti, elementi:

●l’irripetibilità di natura oggettiva cioè l’impossibilità oggettiva di procurare il contraddittorio sulla fonte di prova;

●il consenso dell’imputato;

●la condotta illecita che impedisca il verificarsi del contraddittorio..."


http://www.law.cornell.edu/supremecourt/text/384/1

...."'(I)f there was here a denial of cross-examination without waiver, it would be constitutional error of the first magnitude and no amount of showing of want of prejudice would cure it.'.."

.."The Sixth Amendment provides that: 'In all criminal prosecutions, the accused shall enjoy the right * * * to be confronted with the witnesses against him * * *.' And in Pointer v. State of Texas, 380 U.S. 400, 406, 85 S.Ct. 1065, 1069, 13 L.Ed.2d 923, we held that the confrontation guarantee of the Sixth Amendment including the right of cross-examination 'is 'to be enforced against the States under the Fourteenth Amendment according to the same standards that protect those personal rights against federal encroachment.' Malloy v. Hogan, supra, 378 U.S. 1, at 10, 84 S.Ct. (1489) at 1495 (12 L.Ed.2d 653).' See also Douglas v. State of Alabama, 380 U.S. 415, 85 S.Ct. 1074, 13 L.Ed.2d 934. It follows that unless petitioner did actually waive his right to be confronted with and to cross-examine these witnesses, his federally guaranteed constitutional rights have been denied in two ways..."